Transport mechanism and furnace utilized in the fabrication of semiconductor devices

ABSTRACT

A transport mechanism and furnace for transistor header assemblies is described wherein the headers are transported in a serial manner along a fixed surface. The surface can be formed as a portion of the heat sink of a furnace used to effect soldered connections in semiconductor assemblies. As a result, the headers are heated by conduction. A pair of spaced parallel rods are slidably mounted proximate to the fixed surface and the headers are positioned therebetween. The spacing of these rods is less than the major dimension or length of the header. The application of force to the first header in the series urges the header into frictional engagement with the rods and by simultaneously moving the rods forward all of the headers become frictionally engaged and move through the furnace with the rods. Consequently, the header assemblies are transported without requiring a moving belt and the soldering conditions in the furnace are improved.

United States Patent [72] Inventor Dale T. Kelley Phoenix, Ariz.

121 Appl. No. 784,869

I 22] Filed Dec. 18, 1968 [45] Patented Apr. 20, 1971 [73] Assignee Motorola, Inc.

Franklin Park, Ill.

[54] TRANSPORT MECHANISM AND FURNACE UTILIZED IN THE FABRICATION OF SEMICONDUCTOR DEVICES 11 Claims, 6 Drawing Figs.

[52] US. Cl

5| Int. Cl F2 [50] Field of Search [56] References Cited UNITED STATES PATENTS 1,712,831 5/1929 Laurence 3,294,261 12/1966 Cloutier, .Ir 263/6X Primary Examiner.lohn J. Camby Attorney-Mueller and Aichele ABSTRACT: A transport mechanism and furnace for transistor header assemblies is described wherein the headers are transported in a serial manner along a fixed surface. The surface can be formed as a portion of the heat sink of a furnace used to effect soldered connections in semiconductor assemblies. As a result, the headers are heated by conduction. A pair of spaced parallel rods are slidably mounted proximate to the fixed surface and the headers are positioned therebetween. The spacing of these rods is less than the major dimension or length of the header. The application of force to the first header in the series urges the header into frictional engagement with the rods and by simultaneously moving the rods forward all of the headers become frictionally engaged and move through the furnace with the rods. Consequently, the header assemblies are transported without requiring a moving belt and the soldering conditions in the furnace are improved.

Patented April 20, 1971 3,575,393

4 Sheets-Sheet 1 N In FIG la INVENTOR.

Dale I Kelley I Pmmed' April 20, 1911 4 Sheets-Sheet 4 DIRECTION OF E TRANSPORT FIG 4 INVENTOR. Dale T Kelley 72mm. W, flwmm TRANSPORT MECHANISM AND FURNACE UTILIZED IN THE FABRICATION OF SEMICONDUCTOR DEVICES BACKGROUND OF THE INVENTION This invention relates to apparatus for transporting articles between work stations and in particular to apparatus for transporting partially fabricated semiconductor elements through a furnace.

The increasing usage of solid-state semiconductor devices in large. quantities is due primarily to the performance characteristics and cost of the relatively small elements. Since the electrical components of these devices are contained within relatively small semiconductor dice, a major problem has been the affixation of the external electrical connections thereto. When the components have been formed within the individual dice and the interconnections have been provided, the die is normally located on a metallic header. The header serves as a reference electrode, supporting structure for the die and combination heat transfer means when positioned adjacent to a heat sink. in addition, insulated lead-throughs are generally provided in the header to permit plug-in type operation of the completed structure. Since the completed devices are sold for many different uses, the dimensions, shape and location of the lead-throughs in the header have been standardized in the electronics industry. For example, the header designated as TO-3 is employed throughout the industry for many types of silicon power transistors. These headers are characterized by a curved edge outline which is essentially diamond-shaped.

In the manufacturing operation, the semiconductor die containing the components and the interconnections therebetween is positioned in a receiving recess located in the surface of the header. A small quantity of solder, typically in the form of a disc, is interposed between the header and the die so that good electrical and mechanical contact is provided. The. lead-throughs extend in an insulating sleeve through the header and are provided with a cliplike member which extends over the die. On the side adjacent the die, the clip member is provided with solder to effect an electrical contact during subsequent processing.

The soldered electrical contacts are formed by passing the partially fabricated device through a furnace. The conventional method of transporting the headers through the furnace and to subsequent work stations utilizes a conveyor belt wherein the devices are continuously fed through the furnace in a serial manner. The use of a conveyor wherein the partially fabricated devices are continuously moving has been found difficult to coordinate with subsequent automatic assembly operations since the devices have to be removed or the belt operated intermittently to achieve indexing for the next operation.

The characteristics of the fabricated device are determined in part by the quality of the soldered connections effected in the furnace. Consequently, the temperature and its gradient, as well as the atmosphere in the furnace, have to be rigidly controlled. The temperature of the furnace is important since the solder must flow to effect a relatively large area contact which has good electrical, thermal and mechanical properties. However, the temperature cannot be raised too high or the electrical properties of the semiconductor die may be altered and/or the silver metallization on the die normally utilized in the die-to-header connection can be attacked and the silver dissolved away causing an inferior electrical and thermal connection and one which may fail completely soon after the device is placed in use. It should be noted that the silver thickness on the die and the amount of silver which may be added to the solder are fixed by other processing limitations. Furthennore, the oxygen and/or moisture content of the furnace atmosphere is required to be minimized since the heated semiconductor and metal materials can readily become oxidized and provide unacceptable electrical contacts.

LII

In practice, the air and moisture adsorbed on a conveyor belt is continually being fed into the furnace to contaminate the environment. Since adsorption is a function of surface area, the broad area of the belt is found to contribute greatly to the presence of oxygen in the furnace. In addition, the dynamic character of a conveyor belt creates additional problems in that the header and parts thereon are not in direct contact with the copper core of the furnace. The heating occurs by the process of convection which is recognized as being less efficient than conduction. Further, the lack of close baffling at the input and output apertures inherent in the design of a typical belt furnace contributes to the contamination of the environment. Since the headers and associated parts are transported rather loosely on the belt which, due to its support and guide means, is also substantially wider than the header width, relatively large clearances must be maintained and, thus, the baffling is relatively inefficient.

Accordingly, the present invention is directed to apparatus for transporting articles having a curved edge outline on a fixed or static support surface. In addition, the apparatus is particularly well-suited for transporting partially fabricated semiconductor devices through a furnace to a subsequent work station. Also, the apparatus provides an improved transport means for either hand or mechanical assembly of semiconductor devices. Among the advantages provided by the present invention are noncontinuous movement of the articles and the indexing thereof to facilitate assembly. In addition, the apparatus provides enhanced soldering conditions due to improved baffling of the furnace, lower oxygen and/or moisture content in the furnace atmosphere, conduction heating of the partially fabricated devices, lower furnace temperatures to effect electrical contacts and a higher yield on the processed devices.

SUMMARY OF THE INVENTION The apparatus for transporting articles in accordance with the present invention includes a support means which provides the fixed or static surface upon which the articles are to be transported in a first direction. First and second guide elements are slidably mounted proximate to the surface of the support means and extend in a first direction. The first and second guide elements are mounted in spaced relationship with the articles being located therebetween. Since the articles have a curved edge outline, for example, a conventional header for a semiconductor device, the articles positioned between the guide elements need not be in contact with the elements. However, the guide elements are spaced with respect to the size of the articles so that the articles therebetween are positioned in a substantially serial manner.

A means for applying a force to one of the articles positioned between the guide elements is located at one end of the guide elements. When applied to the article having a curved edge outline, the force may be considered as having two components; one of which is in the direction of travel of the articles, herein referred to as the first direction, and the other in a direction normal to the guide elements. Consequently, the force urges at least the article to which it is directly applied into frictional engagement with the guide elements.

ln addition, driving means are coupled to the guide elements for supplying a driving force to the slidably mounted guide elements which causes them to move in the first direction. The combined effect of the applied force urging at least the initial article into engagement with the guide elements and the movement of the guide elements themselves results in the movement of all of the articles into a position of frictional engagement and the movement of the serially positioned articles forward.

The forward movement of the articles on the static support surface generally continues until either the force applied to 'the last article or the driving force applied to the guide elements is removed. The force applied directly to the article is advantageously provided by a push rod and a stop means can be located at a predetermined point to terminate the movement of the push rod and the force applied thereby. Thus, the stop means determines when the articles are to stop being urged in frictional engagement and no longer transported, as well as indexing the articles. In practice, the driving means and force means can be operated in synchronism.

Further features and advantages of the invention will become more readily apparent from the following detailed description of a specific embodiment of the invention when viewed in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. la and lb provide a top view of one embodiment of the invention.

FIG. 2 is a side view in partial section of the embodiment of FIG. Ia.

FIG. 3 is a cross-sectional view taken along lines 3-3 of FIG. la.

FIG. 4 is a top view of a portion of the support surface and guide elements of the embodiment of FIGS. la and lb containing header elements.

FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. lb.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIGS. Ia and 2, the transport apparatus is shown comprising a mounting plate II having fixedly mounted thereon a way housing 12 and a pillow block 13. Pillow block 13 provides a bearing seat for drive shaft 14 extending therethrough. Drive shaft 14 is coupled at one end via drive chain I5 to a motor (not shown). The other end of drive shaft 14 is provided with drive cam 16.

Drive rod 18 is provided with forward drive roller 20 and return drive roller 21 as shown. These rollers are in contact with drive cam 16 and, when the drive cam is rotated, the rollers provide a reciprocating motion for the rod I8. It will be noted from FIG. la that drive rod 18 extends downwardly through a slotted opening 24 in push bar 30 and a corresponding slotted opening in way housing I2 and is fastened by bolts 22 and 23 to the movable upper section 25 of a conventional dovetail way. The lower section 26 of the way is clamped by bolts 27, 28 to mounting plate II. In operation, the rotation of drive shaft 14 is translated to a reciprocating movement of drive rod 18. While the embodiment shown utilizes a return roller 21, it will be recognized that many different types of biasing means can be utilized to provide a return drive force.

- A fixed or static surface 3] along which the articles are to be transported is provided by rail 56 which is attached to the end of way housing 12 and extends outwardly therefrom. The surface is mounted flush with the top section of the way housing which in effect is utilized as an extension thereof. This extension of the surface is defined by guide plates 32, 33, 34 and 35 affixed to the top of way housing 12. As shown in FIG. la, push bar 30 is located at the end of the surface defined by the guide plates.

The push bar 30 is coupled to the drive cam 16 by drive rod 18 and the rollers attached thereto. The push bar is shown in FIGS. la and 2 in the fully retracted position and when drive cam 16 is rotated, the bar travels forward between guide plates 32 and 33. The drive force for push bar 30 is provided by the drive rod 18 in combination with pin 37 which extends through the transverse slot 40 in the downward extension of drive rod 18 and the adjacent portions of push bar 30. As

.shown more clearly in FIG. 2, pin 36 is rigidly mounted in the push bar while pin 37 is located within the guide slot 40. The pins are coupled to the opposing ends of spring members 38 and 39 as seen in FIGS. and 2. As mentioned previously, bolts 22 and 23 extend downwardly through drive rod 18 to corresponding seats in the movable upper section 25 of the way in housing 12. When the drive rod moves from the retracted position as shown, the push bar 30 and the upper section 25 of the way are driven forward. Since the way section 25 is rigidly attached to drive rod 18, it continues moving forward until the rotation of the drive cam 16 reverses the motion of the drive rod. However, the push bar 30 encounters stop plate 41 prior to the time that drive shaft 14 and drive cam 16 have completed a rotation of l8().

The stop plate 41 is mounted atop guide plates 32 and 33 and extends across the surface upon which the articles are to be transported. The stop plate is spaced from the surface by a distance sufficient to permit the partially fabricated semiconductor devices to move freely thereunder but is positioned so that it will engage the push bar. When the push bar 30 reaches the limit of its forward travel as defined by the location of stop plate 41, the drive rod 18 and upper way section 25 continue moving forward until a rotation of the drive cam occurs. During this interval, the pin 37 contained in the downwardly extending portion of the drive rod 18 moves along transverse slot 40 against the biasing force provided by springs 38 and 39. When the drive rod is moving in the opposite direction, pin 37 returns to the end of slot 40 and the push bar is then returned to the retracted position as shown.

The upper section 25 of the way in housing 12 has a flat large area extension plate 43 affixed to the top thereof. Plate 43, as shown in FIGS. la and 2, extends out of the housing 43 and under a portion of the rail 56. The outwardly extending end of plate 43 is provided with a connecting block 44 on its upper surface. First and second guide rods 50 and 51 extend through the connecting block along the article transport surface 31 of rail 56 in spaced parallel relationship. The guide rods 50 and 51 are slidably mounted in a plurality of guide rod supports 52 and 53 respectively which are periodically spaced along the rail 56. In addition to permitting the guide rods to be moved therethrough, the supports 52 and 53 position the guide rods proximate to the article transport surface so that articles on the surface can contact the rods.

The guide rods 50 and 51 are fastened to connecting block 44 so that they are driven in a reciprocating manner by the drive rod I8. In addition, each guide is provided at its inner end, i.e., the end closest to the drive rod assembly, with flat portions 54 and 54 respectively. These flat portions are slidably positioned in corresponding grooves in guide plates 32 and 33 and in effect may be considered as extensions of the guide rods over the way housing l2. Thus, these extensions are also reciprocally driven by the drive rod 18.

The structural relationship of the guide rods 50 and 51, the support elements 52 and 53 and the rail 56 are shown in the cross-sectional view of FIG. 3. The rail 56, which defines the article transport surface 31, is provided with slots 55 to accommodate the protruding portions of the articles being transported, for example, the emitter and base lead-throughs on transistor headers. Since the articles are moved on the surface 31 or rail 56 and 56, this surface is normally a ground surface outside the furnace and nickel and chromium plated inside to reduce frictional forces and provide an even surface. In addition, the nickel-chromium plating within the furnace, shown in cross section in FIG. 5, provides a nonsolderable surface which is not lost by diffusion into the copper rail 56' which in combination with heat sink 58 forms the hot core of the furnace.

Each guide rod is contained in the corresponding support elements 52, 53 so that an inner portion of the rod is exposed to the articles. The exposed portion of the rod and the sections of rod between spaced support elements are located proximate to the surface 31 so that articles on the surface can be in contact therewith. The support elements are fastened to the rails 56 by bolts (not shown) at spacings sufficient to insure that the rods are maintained substantially parallel along their length. In practice, supports 52 and 53 are formed of a material having a low coefficient of friction such as nylon or Teflon.

Referring again to FIGS. and 2, guide plates 34 and 35 are shown extending outwardly and upwardly at an angle from the push bar 30. The spacing between these plates is equal to the spacing between guide plates 32 and 33. The plates 34 and 35 form a gravity feed means for serially introducing the articles being transported into the region between guide plates 32 and 33. Although a gravity feed means is shown, other types of feed apparatus may be utilized if desired.

The articles supplied to the transport mechanism are characterized by a curved edge outline such as transistor headers. A plurality of headers 60 are shown on surface 31 in FIG. 4. The conventional header is essentially diamondshaped with rounded comersand contains major and minor dimensions measured between opposing corners. The guide rods 50 and 51 are spaced apart a distance which is less than the major dimension of the headers so that the headers assume approximately the position outlined in HO. 4. in the embodiment shown, the major dimension of the headers forms an angle of approximately with the direction of transport As the headers are inserted between guide plates 34 and 35, one of the headers is positioned in thefront of the push bar 30 when it is in its retracted position. When the push bar begins to move forward due to the rotation of drive cam 16 from the position shown in FlGS. la and 2, the headeris pushed forward to a new position between guide plates 32 and 33. The distance that the header is moved is determined primarily by the location of stop plate 41 which limits the forward travel of the push bar.

When the push bar returns to its retracted position, another header is fed from between guide plates 34 and into the space provided by the withdrawal of the push bar. Again, the forward movement of the push bar applies a force to the adjacent header which is transmitted to other header elements positioned between the guide plates 32 and 33 and the guide rods and 5 1. During theinitial start-up operation, the force applied by the push bar is sufficient to drive a number of headers forward due to the relatively low coefficient of friction of the chromium plated surface 31 upon which they travel. However, the transport apparatus is required to move large numbers of headers containing semiconductor assemblies thereon through relatively long furnaces, cooling chambers, cleaning chambers or scrubbers as they are commonly referred to, and to additional work stations, Consequently, the number of headers on the surface 3l of rail 56 may be of the order of several hundred. The movement of a relatively large number of headers on a static surface cannot in practice be obtained by the application of a single force to the last header on the line. The present transport apparatus overcomes this limitation by utilizing a combination of moving guide rods and the push bar.

The combined action which enables a large number of headers to be transported with a relatively small force applied by the push bar relies on the force applied by the bar to the adjacent article to urge all articles on the transport surface into frictional engagement with the guide rods. This action is explained with reference to FIG. 4 wherein a plurality of headers are shown on a portion of the surface 31 of rail 56 prior to the application of a force thereto. The force, applied in the direction of the arrow, is due to the contact of the bar with a preceding header and is transmitted to header 60'. The direction of transport shown by the arrow is the same as the direction of the applied force. The guide rods 50 and 5] are slidably mounted in supports 52 and 53 and at this point in time are about to reverse direction and move in the direction of transport.

The previous description of the mechanism shown in FIGS. la and 2 pointed out that both push bar 30 and guide rods 50 and 51 are operatively connected to driverod 18. Thus, the force is applied to the headers at approximately the same time that the guide rods are driven in the direction of transport. The force applied to header 60' against 60 can be considered as including a component which imparts rotationthereto. The rotation of the header results in a cam-clutch type of operation in that the spacing of the guide rods is less than the major dimension of the header so that the header will contact the rods. The frictional engagement of header 60 with the rods results in the header being transported in the direction of the arrow of FIG. 4. The header 60 then contacts the adjacent header and urges it into frictional engagement with the rods. This action continues down the line with all headers being transported due to the combined action of the push bar and the drive rods. The movement of the articles along surface 31 continues until the push bar 30 encounters the stop plate and the force urging the headersinto frictional engagement with the rods is terminated. As mentioned previously, the push bar then returns to its retracted position and an additional header is fed'into position adjacent the end of the push rod. Although in this particular embodiment, the stop plate terminates the application of the force prior to the termination of the forward movement of the guide rods, other embodiments of the invention have been tested and operated wherein the push rod and the guide rods simultaneously stop and reverse the direction of travel. The advantages obtained by terminating the force prior to the rod movement will later be discussed.

While the description refers to an embodiment utilized in the transporting of headers for semiconductor device fabrication, other types of articles having curved edge outlines can be similarly transported.

Referring now to FIG. lb, the rail 56 is shown entering scrubber unit 61, furnace 62 and cooling chamber 63. These operations are performed on the partially assembled semiconductor devices to effect the soldered connections therein which provide the desired unitary construction. The prior steps of mechanically locating theappropriate parts on the header are performed by conventional assembly techniques while the headers are located on the surface of the rail. Since the forward motion of the headers is intermittent with predetermined forward increments, the individual headers are indexed for these assembly steps. When the devices enter the scrubber unit on the slotted surface of rail 56, they are subjected to either a nitrogen or forming gas environment which flows in through the indicated passage and out through the opening wherein the devices enter. The scrubber is not generally heated and serves to remove trapped air from the devices prior to their entry into the furnace 62. The scrubbing operation is utilized to reduce the entry of oxygen and water vapor into the furnace which are known to adversely affect the soldering process and also the electrical and mechanical qualities of the soldered connections.

In the furnace, the devices are heated to a temperature of approximately 400 C. in a hydrogen atmosphere to thereby form the soldered connections. Previous soldering operations were formed in belt furnaces having a hydrogen atmosphere at a temperature of about 520 C. in order to heat the solder to a temperature of. about 430 C. Since the semiconductor die has .a low mass, the die may be heated to a temperature substantially higher than 430 C. and be adversely affected. However, the present combination of transport apparatus and furnace eliminates overheating due to gradients required in the furnace. Significant increases in the manufacturing yield are obtained at lower temperatures with the transport apparatus and furnace. Previously, the partially fabricated devices were conveyed from the scrubber to the furnace on a conveyor belt and relatively large openings had to be provided for the belt. The present apparatus enables'the baffling to be substantially improved and essentially eliminates the transporting of large quantities of adsorbed air and water into the furnace. This advantage is due to the fact that the support surface in the furnace is fixed or static. Furthermore. the rail 56' and the support surface are preferably made part of the heat sink of the furnace so that a lower furnace temperature can be used to obtain the desired part temperature. As a result of the use of the heat sink as the support surface, the parts are heated by conduction rather than convection so that production rates several times greater than possible for belt furnace of equivalent size can be obtained.

The constructional features of the combined transport apparatus and furnace are shown in FIG. which is a cross section taken along lines 5-5 of HG. lb. The rail 56 is formed of copper and is shaped to fit the contour of the outer stainless steel jacket 57 of the furnace. The upper surface 31 of the rail is provided with the parallel slots previously mentioned which accommodate the downwardly extending contacts of the header assembly shown in Flg. 5. The surface 3] is preferably hard-chromed over a nickel plating to minimize the coefficient of friction and to provide a nonsolderable surface which will not diffuse into the copper rail 56'. The guide rods 50 and 51 proximate to the surface are continuations of the same guide rods previously described and are also provided with a hard chromium surface. The guide rod supports 52 and 53 are preferably formed of graphite.

As shown in FIG. 5, the copper rail 56' forming the bottom heat sink for the furnace is bolted to a mating upper heat sink 58 also formed of copper. A stainless steel baffle plate 59 is removably fastened to the heat sink 58 and enables the clearance between the heat sink and the header or. in other words, the baffiing of the furnace to be changed for different devices. Since the copper rail and upper heat sinks form the hot core and extend the length of the furnace and the header to be heated is in direct contact therewith, the header and the parts thereon are heated primarily by conduction to a temperature which is essentially that of the core itself. The small amount of clearance between the device being formed on the header and the upper heat sink not only substantially reduces heat loss but also minimizes the amount of hydrogen utilized. Due to the combination of the tight baffiing and the static support surface. less oxygen and water vapor are introduced into the furnace during operation so that large quantities of hydrogen are not required to keep the concentration of moisture in the hydrogen atmosphere at a low level. In addition, the reduction of the oxygen and moisture content in the furnace atmosphere enhances the soldering conditions for effecting the mechanical and electrical connections of the semiconductor devices and the manufacturing yields are significantly increased.

The heating of the headers in the hydrogen atmosphere of the furnace not only effects the soldered connections but also removes any oxide films formed thereon. The chemical reduction of the oxide films on the headers results in an increase in the coefficient of friction between the headers and between a header and the guide rods in the furnace. Consequently, the heated articles may have a tendency to adhere slightly to themselves and to the guide rods and move in the reverse direction in embodiments wherein the guide rods and the push rods reverse direction at the same point in time. However, the stop plate which terminates the forward movement of the push rod prior to the termination of the forward motion of the guide rods results in an overtravel of the guide rods relative to the headers, thus freeing them and essentially eliminating this problem. The amount of overtravel provided can be readily controlled for different types of operation by an adjustment or replacement of the stop plate. In addition. the adjustment of the stop plate controls the period of time that the device is heated since it controls the length of the movement of the push bar and therefore the number of cycles for a device to travel on copper rail 56' in the furnace. The control over the period of heating is necessary in applications wherein the apparatus is used to transport different types of devices. Further, the adjustment of the stop plate controls the indexing of the devices with respect to subsequent work stations. While the above description has referred to a specific embodiment of the invention, it is apparent that many variations and modifications may be made thereon without departing from the spirit and scope of the invention.

We claim:

1. Apparatus for transporting articles having a curved edge outline to a work station which comprises:

a. support means for providing a surface upon which said articles are transported in a first direction;

b. first and second guide elements mounted on said support means, said guide elements being mounted in spaced relationship to permit the transporting of articles therebetween, the articles to be transported being positioned between the guide elements;

c. mans for slidably mounting said guide elements proximate to the surface of said support means;

d. drive means coupled to said first and second guide elements for driving said elements in the first direction;

e. means for applying a force to one of the articles positioned between said guide elements, said force means urging the articles into frictional engagement with the guide elements whereby said articles are transported on said support means;

. said first and second guide elements being spaced by a distance which is less than the major dimension of the articles being transported;

. said support means providing a static surface upon which said articles trabel;

. said drive means being coupled to the guide elements for reciprocally driving said elements; and

. and said force means urging said articles into engagement with said guide elements when said elements are driven in the first direction.

2. Apparatus in accordance with claim 1 further comprising stop means for terminating the force urging said articles into engagement with the guide elements when said elements are being driven in the first direction.

3. Apparatus in accordance with claim 2 wherein said means for applying a force to one of the articles positioned between said guide elements comprises a push rod having a contacting end for applying a force to the adjacent article positioned between said guide elements, the duration of the application of said force by the push rod being limited by said stop means, and means for reciprocally driving said push rod.

4. Apparatus for transporting header elements upon which semiconductor elements are fabricated, said header elements having a curved edge outline containing a major dimension and a minor dimension thereacross, which comprises:

a. support means for providing a surface upon which the headers are transported in a first direction;

b. first and second guide elements mounted on said support means, said guide elements being mounted in spaced relationship to permit the transporting of header elements in a serial manner therebetween, the spacing between said guide elements being less than the major dimension of said header elements;

c. means for slidably mounting said guide elements proximate to the surface of said support means;

d. drive means for reciprocally driving said guide elements in the first and opposing directions; and

c. means for applying a force to one of the header elements positioned between said guide elements during the interval that said guide elements are being driven in the first direction, said force urging said header elements into frictional engagement with the guide elements whereby said header elements are transported in the first direction.

5. Apparatus in accordance with claim 4 wherein said means for applying a force to one of the header elements comprises a push rod having a contacting end for applying a force to the adjacent header element and means for reciprocally driving said push rod in the first and opposing direction, said means being operatively connected to the drive means for said guide elements.

6. Apparatus in accordance with claim 5 further comprising stop means for terminating the motion of the push rod during the interval that said guide elements are being driven in the first direction.

7. Apparatus in accordance with claim 6 further comprising means for inserting said header elements between said guide elements during the interval that said guide elements and the push rod are being driven in the opposing direction.

8. Apparatus in accordance with claim 6 wherein said support means comprises a fixed surface having downwardly a. placing a plurality of said articles in a serial configuration extending in the direction along which said articles are to be transported;

b. applying a force to one of said articles which imparts rotation thereto; and

c. concurrently applying a force along the outer edges of the serial configuration of articles, the combination of the force imparting rotation and the force applied along the outer edges of the configuration moving said articles along the surface. 

1. Apparatus for transporting articles having a curved edge outline to a work station which comprises: a. support means for providing a surface upon which said articles are transported in a first direction; b. first and second guide elements mounted on said support means, said guide elements being mounted in spaced relationship to permit the transporting of articles therebetween, the articles to be transported being positioned between the guide elements; c. mans for slidably mounting said guide elements proximate to the surface of said support means; d. drive means coupled to said first and second guide elements for driving said elements in the first direction; e. means for applying a force to one of the articles positioned between said guide elements, said force means urging the articles into frictional engagement with the guide elements whereby said articles are transported on said support means; f. said first and second guide elements being spaced by a distance which is less than the major dimension of the articles being transported; g. said support means providing a static surface upon which said articles trabel; h. said drive means being coupled to the guide elements for reciprocally driving said elements; and i. and said force means urging said articles into engagement with said guide elements when said elements are driven in the first direction.
 2. Apparatus in accordance with claim 1 further comprising stop means for terminating the force urging said articles into engagement with the guide elements when said eleMents are being driven in the first direction.
 3. Apparatus in accordance with claim 2 wherein said means for applying a force to one of the articles positioned between said guide elements comprises a push rod having a contacting end for applying a force to the adjacent article positioned between said guide elements, the duration of the application of said force by the push rod being limited by said stop means, and means for reciprocally driving said push rod.
 4. Apparatus for transporting header elements upon which semiconductor elements are fabricated, said header elements having a curved edge outline containing a major dimension and a minor dimension thereacross, which comprises: a. support means for providing a surface upon which the headers are transported in a first direction; b. first and second guide elements mounted on said support means, said guide elements being mounted in spaced relationship to permit the transporting of header elements in a serial manner therebetween, the spacing between said guide elements being less than the major dimension of said header elements; c. means for slidably mounting said guide elements proximate to the surface of said support means; d. drive means for reciprocally driving said guide elements in the first and opposing directions; and e. means for applying a force to one of the header elements positioned between said guide elements during the interval that said guide elements are being driven in the first direction, said force urging said header elements into frictional engagement with the guide elements whereby said header elements are transported in the first direction.
 5. Apparatus in accordance with claim 4 wherein said means for applying a force to one of the header elements comprises a push rod having a contacting end for applying a force to the adjacent header element and means for reciprocally driving said push rod in the first and opposing direction, said means being operatively connected to the drive means for said guide elements.
 6. Apparatus in accordance with claim 5 further comprising stop means for terminating the motion of the push rod during the interval that said guide elements are being driven in the first direction.
 7. Apparatus in accordance with claim 6 further comprising means for inserting said header elements between said guide elements during the interval that said guide elements and the push rod are being driven in the opposing direction.
 8. Apparatus in accordance with claim 6 wherein said support means comprises a fixed surface having downwardly extending slots therein which extend along said surface in the first direction, said slots accommodating the external electrical contacts affixed to said header.
 9. Apparatus in accordance with claim 8 wherein said support means comprises a copper rail having an upper surface thereof containing said slots.
 10. Apparatus in accordance with claim 9 wherein the upper surface of said copper rail comprises a layer containing chromium.
 11. The method of transporting articles having a curved edge outline along a fixed surface which comprises the following steps: a. placing a plurality of said articles in a serial configuration extending in the direction along which said articles are to be transported; b. applying a force to one of said articles which imparts rotation thereto; and c. concurrently applying a force along the outer edges of the serial configuration of articles, the combination of the force imparting rotation and the force applied along the outer edges of the configuration moving said articles along the surface. 